1. Field of the Invention
The present invention relates to a membrane from a polycarbonate-polyether-blockcopolymer with 5 to 35 weight percent alkyleneether-carbonate units and with 95 to 65 weight percent of repeating bisphenol A-carbonate units.
2. Brief Description of the Background of the
Invention Including Prior Art
Membranes from a polycarbonate-polyether-blockcopolymer with 5 to 35 weight percent repeating alkylenether-carbonate units and with 95 to 65 weight percent of repeating bisphenol A-carbonate units have been disclosed. The German Offenlegungsschrift DE-OS No. 27 13 283 discloses such a polyether-polycarbonate-blockcopolymer membrane having properties substantially directed toward a relatively high dialytical permeability for vitamine B 12 at a low ultrafiltration rate. The intrinsic viscosities following from the indicated molecular weights are under 170 ml/g and for ultrafiltration values should be maintained which are below of 4 ml/h.m.sup.2.mm Hg. The mechanical properties of such membrane are only little satisfactory.
Most recently, memofiltration has been introduced as a treatment method for dialysis patients suffering from high blood pressure. In order to reinfuse larger amounts of liquid into the human blood circulation membranes are required for the dialysis treatment, which have a high hydraulic permeability.
Conventionally, the membranes of polycarbonate-polyether-copolymer were prepared (compare for example U.S. Pat. No. 4,048,271 and German Offenlegungsschrift DE-OS No. 27 11 498) by scraping on of a thinned polymer solution containing a material for the formation of pores onto a surface followed by partial evaporation of the solvent. After the partial evaporation of the solvent the membranes were jellied in a water bath. After washing the membranes were stored in a plastic bag or another container containing water and a sterilizing agent such as for example formaldehyde.